Stud insert for shielding electrical conductors, and the like



Oct. 12, 1965 HElMAN 3,211,824

STUD INSERT FOR SHIELDING ELECTRICAL GONDUCTORS, AND THE LIKE Filed Jan.I50, 1964 INVENTOR JORD N L. HEIMN Z1 ATTORNEY United States Patent3,211,824 STUD INSERT FOR SHIELDING ELECTRICAL CONDUCTORS, AND THE LIKEJordan L. Heiman, Olivette, Mo., assignor to International Oil BurnerCompany, St. Louis, Mo., a corporation of Missouri Filed Jan. 30, 1964,Ser. No. 341,358

8 Claims. (Cl. 17448) The present invention relates to an article forshielding electrical wires and the like, to be inserted in the studs ofwalls of mobile houses, for example; and to the method of constructingsuch walls.

In the construction of hollow walls for mobile homes, the exteriorsheet, usually a metal sheet such as aluminum, and the interior sheet,which may be a decorative interior sheet of plywood, are secured toclosely spaced wooden studs which support and structurally reinforce thewall. Electrical wires are customarily concealed within the walls bystringing them through notched-out grooves provided in the wooden studs.

Because of the close spacing of the wooden studs, it is difficult toposition a drill between them to bore holes through which the electricalwires may be strung. Therefore, to expedite assembly of the walls, arouting tool is passed over the inside surface of the wooden studs,

thereby providing the notched-out grooves which receive the electricalwires.

This method has not proved satisfactory where the inner and outer wallboards are secured to the studs by randomly spaced fasteners. Onedifliculty encountered has been that the randomly spaced nails, staplesor other fasteners pierce the insulation of the electrical wires,causing short circuits to be developed. Such short circuits are notdetected until the wall has been completely assembled. If detected atthis time, an expensive and time-consuming dismantling of the wall isrequired to locate and to correct the defect. Another difficulty is thatthe grooves Weaken the wooden studs, and accordingly, the wallstructure.

The general purpose of this invention is to provide a method and articlefor shielding electrical wires concealed in hollow walls, wherein allthe advantages of customar- .ily employed methods and apparatus areretained, and

none of the aforedescribed disadvantages are encountered. Thereforeamong the objects of the present invention are the provisions of:

A metal shield for electrical wire which may be readily manufacturedwithout welding or extrusion; a shield having sufficient structuralstrength to prevent penetration by fasteners and reinforced againstinward forces applied to its exterior surface;

A metal shield for hammering into a wooden stud groove which exhibitsspring-like defiectance on insertion to tightly engage the shieldtherein;

A metal shield for hammering into a wooden stud which is open to receiveelectrical wires therein and is closeable upon hammering into the stud;and

A method of building hollow Walls of the type including wooden studs towhich structural and decorative sheets are to be fastened, wherebybending strength of the grooved studs is restored by the compressivestrength of the shield and the tensile strength of the structural sheetsfastened thereto.

In the present invention these purposes (as well as others apparentherein) are achieved generally by providing a one-piece tubular shieldfor electrical conductors, adapted to be driven into a groove in awooden stud over which structural sheets are to be fastened. The shieldconsists of an elongated metal strip of sutficient structural strengthto prevent penetration by the sheet fasteners.

3,211,824 Patented Oct. 12, 1965 ice The metal strip is bent into aclosed, hollow cross-section having unsecured strip ends adjacent towhich two substantially plane walls are formed. These walls form acorner; one wall having an unsecured end, at least a portion of whichabuts the interior surface of the other wall. Fastening means areprovided on two opposite horizontal walls and project outwardly tosecure the strip within the grooved stud.

The method utilized in practicing the present invention consistsgenerally of: routing the studs to provide laterally thereacrossrectangular notches whose depth do not exceed half the depth of thestuds, force-fitting within each rectangular notch a rectangular metalshield member hollow transversely to the stud, inserting electricalwiring through the metal shield member, and randomly fastening thestructural sheets to the outer side of the studs. Accordingly, thosenails or staples driven into the wall, at the stud locations, whichhappen to strike the shields will be turned harmlessly aside.

Utilization of the invention will become apparent to those skilled inthe art from the disclosures made in the following detailed descriptionof the preferred embodiment of the invention as illustrated in theaccompanying drawings, in which:

FIG. 1 is a perspective sketch of the tubular shield showing thereinforcing top wall bent to engage the vertical side wall and thefastening tabs;

FIG. 2 is a plan view of the tubular shield of FIG. 1 illustrating thetop portion of the shield and the protruding pointed tab used insecuring the shield;

FIG. 3 is a plan view illustrating a modification of the pointed tabused in securing the shield of FIG. 1 to wooden studs;

FIG. 4 is a side edge view of the metal strip as it appears beforebending into the tubular shield of FIG. 1;

FIG. 5 is a cross-sectional view of the tubular shield of FIG. 1 showninserted in a groove provided in a wooden stud which supports interiorand exterior surface sheets; and

FIG. 6 is a perspective sketch of a second embodiment of the presentinvention showing the reinforcing wall with an inwardly protruding taband the rear wall having arcuately bowed portions extending inwardly.

Referring now to the drawings, wherein like reference charactersdesignate like or corresponding parts throughout the several views,there is shown in FIG. 1 a onepiece tubular shield, generally designated10, formed to be inserted in notched-out grooves provided in thevertical wooden studs used in the construction illustrated. This tubularshield 10 consists of an elongated metal strip 12 which is bent into anopen-ended, rectangular cross section having two unsecured ends 14 and16. By bending the metal strip 12 in this fashion, two substantiallyvertical walls are formed to meet two substantially horizontal walls atthree bent corners 18 and a fourth, closing corner 20, formed by theintersection of the unsecured end 16 and one of the vertical walls. Thetwo horizontal walls are generally designated as a top wall 22 and thebottom wall 24, while the vertical walls are generally designated as afront wall 26 and a rear wall 28. Preferably the metal strip 12 is coldrolled steel which exhibits a degree of hardness sufficient to preventpenetration by commonly employed sheet fasteners utilized in wallconstruction. It has been found that 16-gauge coldrolled steel can bereadily bent into the configuration illustrated and prevents penetrationof the tubular shield 10 by conventional sheet nails, staples, screws,and the tools used in inserting them.

The closing corner 20 of the tubular shield 10 is formed so that,although having unsecured ends, it structurally reinforces itself toresist deformation and inward forces applied to its exterior surface.

To this end, the top wall 22 has a bent margin 30 which extendsangu-l-arly, subtending an angle greater than 90 and downwardterminating in the unsecured end 16 at the hereinbefore referred toclosing corner 20. This unsecured end 16 is presented abuttingly againstthe interior surface 32 of the shields rear wall 28. Because the bentmargin 30 intersects the rear wall 28 inwardly of its terminatingunsecured end 514, it reinfior-ces the shields rear wall 28 againstinward forces; for example, against nails or screws driven against it infastening the exterior :aluminum sheet onto the studs. The angularlybent margin '30 presented to the interior surface '32 of the rear wall28 inwardly of its terminus permits a spring-like deflect-ance of thetubular shield .10 on being driven into the grooves of the studs. Thisspring-like detlectance allows upper and lower fastening means,generally designated 34, to press into the groove of a wooden stud andtightly engage the tubular shield 10 therein.

The fastening means referred to hereinabove takes the form of integralpointed tabs 84 which project outwardly from the top and bottom walls 22and 24 of the hollow shield. These tabs 34 are preferably stamped-out,arrowhead-like spikes having their pointed ends extending toward theshields vertical front wall 2 6.

FIG. 3 shows a modified pointed tab 34 especially suited for use wherethe notched-out groove in the wooden stud has been made too large for :atight fit between it and the tubular shield 10. The pointed tab 34, likethe pointed tabs 34, project outwardly from the top and bottom walls *22and 24 respectively and toward the front wall 26. However, the pointedtabs 34' are provided with doublepointed tips 36 forming a V-shapednotch 37 therebetween. If such loose fit exists between the tubularshield 10 and such groove in the wooden stud, a nail may be driventhrough this notch 37 and into the wooden stud to secure the tubularshield within the notched-out groove.

FIG. 4 shows the metal strip 12 as it appears prior to the bendingoperation which closes it to provide the finished product shown inFIG. 1. The metal strip 12 is cut off from a longer strip of thematerial to form the unsecured ends 14 and 1 6. In the next operationthe pointed tabs 34 and the bent-down margin 30 are formed. The finaloperation involves the bending of the metal strip -12 at the pointsindicated by the dashed lines I, whereupon the open-ended tubular shield10 of FIG. 1 results.

In the construction of hollow walls for mobile homes, where closelyspaced wooden studs have tension-resisting structural sheets fastened totheir outer sides and through which it is desired to install electricalwiring, a routing tool is passed over the interior edge surfaces 38 ofthe wood-en studs 39 to provide the notched-out grooves 40 (see FIG. fora single stud 39 :and groove 40). In order not to substantially weakenthe Wooden studs 39 therectangular grooves 40, which extend transverselyacross the entire interior edge surface 38 of the studs, should not bepermitted to exceed half of the depth of the stud which separates theinterior and exterior sheets to be applied. The tubular shield .10 isthen force-fitted into a notchedout groove 40 of a rear wall 28 iir'st,and driven therein by hammering the front shield wall 26 until it isflush with the interior edge surface '38 of the stud 39. As the tubularshield is driven into the rectangular, notched-out groove 40 thebent-down margin 30 of its top wall 22 reinforces the rear wall 28 toprevent it from being deflected into the hollow interior of the tubularshield. Nevertheless, the spring-like defiectance of the shield .10permits wedge-like engagement of its pointed tabs 34 into the woo-denstud 39, The tabs 34 serve as barbs to prevent the shield from movingtransversely or outwardly from the groove 40.

Electrical Wiring may then be inserted through the metal tubular shieldmember 10. After the electrical wires have been installed within thetubular shield !10 in the stud, an interior sheet 42, of decorativeplywood or the like, may

then be randomly fastened to the wooden studs 39 by the fasteners 44,for example nail-s, screws, staples, or the like. if any fasteners 44 bedirected toward the electrical conductors 46, they are deflected by themetal tubular shield M as shown, thereby preventing the short circuitingof the electrical conductors 46. In like manner, when an exteriorstructural sheet 48 is secured by randomly spaced fasteners 44,interference with the electrical conductors 46 by the fasteners 44 isprevented by the rear wall 28. Because the rear wall .28 is reinforcedby the top wall margin 30, a fastener 44, so driven, will not causecollapse of the rear wall 28 against the conductors 46-.

In addition to shielding the electrical conductors 44, the tubularshield .10 rest-ores the structural strength of the stud by contributingits compressive strength to replace that lost by grooving the wood. Thestructural sheets 42, 48, which are strong in tension work with thestuds 39 to resist bending loads. When the interior structural sheet 42is in tension, its strength in tension is adequate to resist the imposedload, regardless of the groove. If the bending load be reversed, to putthe interior in compression, the tubular shield 10 resists suchcompression. Accordingly, the present method prevents structuralfailures which might otherwise occur due to the weakening of the "studsby the grooves 40.

In FIG. 6, there is shown a modification of the tubular shield member10' wherein the top wall 22', rather than having a bent down marginportion, extends horizontally throughout its entire length to terminatein an unsecured end 16. This unsecured end 16 is provided with anindented, inwardly protruding reinforcing tab '50 which serves to abutthe interior surface of the rear wall 2 8' inwardly of its terminusunsecured end 14'. Preferably the tab 50 abuts the rear wall 28'intermediate the side edges at the approximate middle thereof. The rearwall 28 consists of :a flat, plane mid-portion 52 which terminates oneach side in inwardly-extending, arcuately bowed portions 54, Theinwardly extending bowed portions 54 serve to abut the inner surface ofthe topwall 22' and reinforce same.

In fabricating the tubular shield member 10, the bending operation issuch that the bottom wall 24 and the rear wall .28 form an angle greaterthan as shown in FIG. 6. This provides an opening 56 between theunsecured ends .14 and 16' through which electrical wiring may beinserted prior to closing. Upon force-fitting the shield member 10' intoa wooden stud, the rear wall 28' is bent around the corner 18' to closethe opening 56 and the tabs 34' secure it to the stud. Reinforcing tab50 impends the bending of the rear wall 28' past the vertical positionand the bowed portions 54 of the rear wall 28' reinforce the upper wall22 in this vertical position.

Thus, it may be seen that the present invention provides a uniquetubular shield which may be utilized in the construction of hollow,stud-reinforced walls to house and protect electrical wiring installedtherein and simultaneousy avoid lessening the structural strength of thewall stu s.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. For example, instead ofdriving the fasteners at random, the steel shield can be locatedmagnetically, and the fasteners may then be spaced to avoid them.Furthermore, it should be understood that the steps of inserting theelectrical wires in the metal shield member and force-fitting the shieldmembers into the stud are interchangeable in time sequence. For example,in using the shield member which is partially open after fabrication,the electrical wiring can be inserted and then the shield memberforce-fitted into the stud. The reverse operation is most practicalusing the shield member having the bent down margin. It is therefore tobe understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically described.

Iclaim: 1. A one-piece tubular shield for electrical conductors adaptedto be inserted in wooden studs over which structural sheets are to befastened, comprising an elongated metal strip of suflicient structuralstrength 5 to prevent penetration by the sheet fasteners, said metalstrip being bent into an open-ended hollow rectangular cross-sectionhaving unsecured ends and characterized by two substantially verticalwalls meeting upon closure with two substantially horizontal walls atthree bent corners and at a fourth corner,

said fourth corner being defined by one of said horizontal wallspresenting upon closure one of said unsecured strip ends abuttinglyagainst the interior surface of that adjacent vertical wall which hasits terminus in the other unsecured strip end whereby said vertical wallis reinforced against inward forces applied to its exterior surface.

2. The one-piece tubular shield as defined in claim 1,

wherein said horizontal walls have fastening means projecting outwardtherefrom whereby said shield may be secured within the wooden studs.

3. The tubular shield as defined in claim 2, wherein said fasteningmeans are integral pointed tabs which project toward that vertical wallwhich terminates in two bent corners.

4. The tubular shield as defined in claim 3, wherein the fastening meansare integral double-pointed tabs, each having a notch between the doublepoints thereof,

whereby in the event of loose fit of the shield within the stud, a nailmay be driven within such notch to secure the shield to the stud.

5. A one-piece tubular shield for electrical conductors adapted to bedriven into a groove in a wooden stud over which structural sheets areto be fastened, comprising tially plane walls forming a corner, one saidwall having an angularly bent margin adjacent to its such ends to abutthe interior surface of the other said wall,

whereby spring-like deflectance of the metal on being so driven intosuch groove tightly engages the shield therein.

6. The tubular shield as defined in claim 5, wherein said angular bendof said margin subtends an angle greater than 7. A one-piece tubularshield for electrical conductors adapted to be driven into a groove in awooden stud over which structural sheets are to be fastened, comprisingan elongated metal strip of sufficient structural strength to preventpenetration by the sheet fasteners, said metal strip being bent into ahollow cross-section including an angle greater than 90 wherebyunsecured strip ends thereof are spaced apart to provide an openingcommunicating with the interior of said bent metal strip,

there being formed adjacent to said unsecured strip ends two walls, oneof said walls having an inwardly protruding tab at its said strip end toabout the interior surface of the other said wall,

whereby upon being driven into such grooved stud the said angle isreduced to 90 and the spaced apart ends are closed together and saidinwardly protruding tab reinforces the other said wall and prevents thereduction of said angle to less than 90.

8. The tubular shield as defined in claim 7, wherein said other wall ischaracterized by inwardly extending bowed portions which upon closureare caused to be aligned below the inner surface of the one said wall.

References Cited by the Examiner

1. A ONE-PIECE TUBULAR SHIELD FOR ELECTRICAL CONDUCTORS ADAPTED TO BEINSERTED IN WOODEN STUDS OVER WHICH STRUCTURAL SHEETS ARE TO BEFASTENED, COMPRISING AN ELONGATED METAL STRIP OF SUFFICIENT STRUCTURALSTRENGTH TO PREVENT PENETRATION BY THE SHEET FASTENERS, SAID METAL STRIPBEING BENT INTO AN OPEN-ENDED HOLLOW RECTANGULAR CROSS-SECTION HAVINGUNSECURED ENDS AND CHARACTERIZED BY TWO SUBSTANTIALLY VERTICAL WALLSMEETING UPON CLOSURE WITH TWO SUBSTANTIALLY HORIZONTAL WALLS AT THREEBENT CORNERS AND AT A FOURTH CORNER, SAID FOURTH CORNER BEING DEFINED BYONE OF SAID HORI-